The event, sponsored by the U.S. Department of State, is a big deal. Normally, we laypeople need to make appointments to get our passports. On Saturday, however, no appointments are necessary at all, so long as you visit a Regional Passport Agency or a select number of Passport Assistance Facilities, which include many metropolitan post offices.

What’s more, passport applicants who file paperwork at these regional agencies usually are required to fork over an extra $60 to expedite processing (which takes 2-3 weeks), but people who go for the docs on Saturday are eligible for standard processing, which is free (and usually takes 4-6 weeks).

Check to see if the location you plan to visit offers photo services. If they don’t, be sure to show up with passport-sized photos of your child. (For official photo requirements, click here.)

Bring a certified copy of your child’s birth certificate, and be prepared to hand it over as part of your passport application package. The State Department will send it back to you once they’ve verified your kids—and, therefore, you—are legitimate citizens.

Don’t sign any of the documents until instructed to do so (trust me on this one; if you goof, you’ve got to fill out the whole packet again).

Arrive with a money order or cashier’s check to cover all fees (which, depending on what you order, likely will be $105 or $120 for kids under the age of 16). If you’re filing paperwork at a post office, don’t worry—these guys sell money orders. If you’re going to one of the formal passport agencies, however, you’ll want to take care of this (perhaps at your local bank) before you arrive. (A list of all fees is here.)

Finally, it’s a good idea to bring games, books and other stuff to keep your kids busy; the passport application process can take a while (and we all know government employees are notoriously slow to begin with). Good luck!